Complex formers for polyvalent metal ions

ABSTRACT

The present invention relates to compounds of the general formula   in which X represents the group   and wherein R is a hydrogen atom, an alkyl radical with 1 to 4 C-atoms or a phenyl radical. These compounds may be used for the preparation of complex compounds with polyvalent metal ions.

United States Patent [191 Heins et al.

[ 51 Dec. 2, 1975 1 COMPLEX FORMERS FOR POLYVALENT METAL IONS [75] Inventors: Arnold Heins, Hilden; Helmut Blum;

Karl-Heinz Worms, both of Duesseldorf-Holthausen, all of Germany [73] Assignee: Bayer Aktiengesellschaft,

Leverkusen, Germany [22] Filed: Apr. 9, 1973 21 App]. No.: 349,347

[30] Foreign Application Priority Data Apr. 13, 1972 Germany 2217692 [52] U.S. Cl.... 260/502.4 R; 204/45 R; 204/D1G. 2; 210/58; 252/8.6; 252/82; 252/89; 252/121;

252/389 R; 252/DIG. 11; 252/DlG. 17;

260/502.4 P; 260/961; 260/DIG. 4 3

3,833,690 9/1974 Kerst 260/502.4 P

OTHER PUBLICATIONS Bull. Acad. Sci. USSR, Dir. Chem. Sci. (English translation) 1952, pp. 821-824.

Primary Examiner.loseph E. Evans Attorney, Agent, or Firm--Burgess, Dinklage & Sprung [57] ABSTRACT The present invention relates to compounds of the general formula in which X represents the group and wherein R is a hydrogen atom. an alkyl radical with 1 to 4 C-atoms or a phenyl radical. These compounds may be used for the preparation of complex compounds with polyvalent metal ions.

10 Claims, No Drawings COMPLEX FORMERS FOR POLYVALENT METAL IONS Compounds of different structure may be used to prevent the precipitation of polyvalent metal ions. Examples of known complex formers include aminoacetic acids or their alkali salts, of which nitrilotriacetic acid and alkylene diamine tetracetic acid are particularly suitable because they effectively bind the salts responsible for hardness in water and also heavy metal ions. Unfortunately, these substances suffer from the disadvantage that they have to be present in stoichiometric quantities in order to obtain complex formation. Polyphosphates are also used for purposes such as these, having the advantage that they are also effective in substoichiometric quantities.

Unfortunately, polyphosphates are not resistant to hydrolysis under certain conditions. It is also undesirable in certain cases to use large quantities in detergents and cleaning agents.

For this reason, some polyphosphonic acids, such as, for example, hydroxyethane diphosphonic acid and aminotrimethylene phosphonic acid, have also been used as complex formers because compounds such as these can also be used in substoichiometric quantities and are resistant to hydrolysis. However, in these compounds, too, the phosphorus content is relatively high.

It has now been found that organic compounds corresponding to the general formula (I) shown below can be used as complex formers, being especially suitable in that they can be used in substoichiometric quantitites, they are resistant to hydrolysis and they have a relatively low phosphorus content. According to the invention, there is provided a compound corresponding to the general formula (I) in which X represents the group:

ion-I (CH2) r wherein R represents hydrogen, alkyl with l to 4 C- atoms and phenyl.

There is also provided a process for the preparation of a complex, in which at least one compound as described above is brought into contact with at least one polyvalent metal ion.

Instead of the acids, it is also possible to use the corresponding water-soluble salts, such as the potassium, sodium or ammonium salts or the salts with organic bases, especially alkanolamines such as monoethanolamine, diethanolamine or triethanolamine. Production can be carried out by completely or partly neutralizing the acids with inorganic or organic bases, such as NaOI-I, KOI-I, NH OH or alkanolamines, and also with alkali carbonates.

The following compounds correspond to the above formula (I): l-phosphonopropanel ,2,3-tricarboxylic acid, l-phosphonobutane-2,3,4-tricarboxylic acid, 1,1-

2 diphosphonopropane-2,3-dicarboxylic acid, 2-phosphonobutane-2,3,4-tricarboxylic acid and 2,2-diphosphonobutane-3,4-dicarboxylic acid. l-phosphonopropane-l ,2,3-tricarboxylic acid can be obtained by reacting maleic acid ester with phosphonoacetic acid ester in the presence of an alcoholate and subsequently hydrolyzing the ester obtained. l-phosphonobutane- 2,3,4-tricarboxylic acid can be obtained by reacting dimethyl phosphite with l-buteneQ,3,4-tricarboxylic acid ester in the presence of a sodium alcoholate and subsequently hydrolyzing the ester obtained to form the required acid.

The reaction of a methylenediphosphonic acid alkyl ester with a maleic acid alkyl ester in the presence of a sodium alcoholate gives an ester which can be converted by acid hydrolysis into 1,1-diphosphonopropane-2,3-dicarboxylic acid.

Z-phosphonobutane-Z,3,4-tricarboxylic acid can be obtained by reacting a-diethyl phosphonopropionic acid methyl ester with maleic acid diethyl ester in the presence of an alcoholate and subsequently hydrolyzing the ester obtained.

2,2-diphosphonobutane-3,4-dicarboxylic acid may be obtained by reacting maleic acid ester with ethanel,l-diphosphonic acid ester in the presence of sodium alcoholate and subsequently subjecting the product obtained to acid hydrolysis.

The phosphonic acids described above can be converted into the corresponding salts in a known manner by neutralization with alkali hydroxides, ammonium hydroxide or mono-, dior tri-ethanolamine.

The above-mentioned compounds, including their alkali metal, ammonium or alkanolamine salts, are effective complex formers for alkaline, earth metal ions, espec'ally calcium ions, and accordingly are particularly useful for water-softening purposes. They do not have to be used in stoichiometric quantities, and indeed the precipitation of calcite can be considerably retarded by using only substoichiometric quantities.

Similarly, they are also eminently suitable for use as corrosion inhibitors and anti-scale agents for cooling water, especially in combination with additives known per se, such as, for example, divalent zinc and/or cadmium salts,orthophosphates, chromates or hydrazine hydrate.

The particular stoichiometric quantity, corresponding to the compound used, can readily be determined through a simple test. In general, the complex formers are used in quantities of from 1 mole per 2,000 moles of metal ions up to 6 times the stoichiometric quantity.

By virtue of the properties referred to above, the new complex formers can also be used, for example, for decrusting fabrics in which alkali salts have been deposited, and for reducing the accumulation of ash in fabrics. They are also suitable for cleaning rigid materials, in particular metal or glass. In particular, they can be used as an additive for bottle-washing agents.

The complex-forming capacity can also be utilized with advantage in systems in which copper ions have an undesirable influence. For example, it can be used to prevent the decomposition of per-compounds or even compounds is also reflected in the fact that the wellknown reddening, which is normally observed when thiocyanate is added to solutions containing a trivalent ion, no longer occurs. Accordingly, these properties can also be utilized with advantage to prevent the deposition of iron compounds, especially iron hydroxide. on fabrics or during bottle washing. The new compounds can also be used instead of cyanides in electroplating baths.

Finally, they are also suitable for use as components with complex-forming properties in detergents and cleaning agents, and can be used in combination with known anion-active. cation-active or non-ionogenic wetting agents. In addition. they can be used in combination with caustic alkalis, alkali carbonates and silicates, phosphates or borates.

The invention is illustrated by the following Examples:

EXAMPLE 1 P C H found: 13.37 44.56 7.37 calculated: 13.48 44.34 7.39

The ester is hydrolyzed by boiling with concentrated hydrochloric acid. l,l-diphosphonopropane-2,3-dicarboxylic acid crystallizes out after purification with active carbon and concentration of the hydrolysis product.

Yield: approximately 100 7r. based on the ester.

The acid accumulates in the monohydrate form and has the following analytical data (in 7c by weight):

P C H found: 1989 19.74 3.85 Calculated: 20.00 19.37 3.87

The molecular weight as determined by potentiometric titration is as follows:

found: 308

calculated: 310

The monohydrate has a melting point of 149 to 150C.

The corresponding salts can be prepared from the acid by neutralization with inorganic bases.

EXAMPLE 2 1-butene-2,3,4-tricarboxylic acid trimethyl ester was reacted at 100 to 1 10C with an equimolar quantity of dimethylphosphite in the presence of a saturated sodium ethylate solution. Neutralization of the ethylate with glacial acetic acid was followed by distillation under high vacuum. The main fraction distilled at 180 to 190C under a pressure of 0.075 to 0.10 mm Hg.

Yield of ester: 80%.

4 The ester obtained has the following analytical data (in 7: by weight):

P C H found: 9.04 42.08 6.17 calculated: 9.12 43.36 6.17

The ester thus obtained was hydrolyzed by boiling with moderately concentrated hydrochloric acid. Following evaporation of the water, l-phosphonobutane- 2,3,4-tricarboxylic acid was obtained in crystalline form.

Yield: 7r, based on the ester.

Analytical data (in 7c by weight):

P C H found: 1 1.18 30.40 3.81 calculated: 1 1.48 31.10 4.07

Melting point: 154 to 155C Molecular weight as determined by potentiometric titration:

found:

275 calculated: 270

EXAMPLE 3 P C H found: 7.94 48.69 7.48 calculated: 7.83 48.49 7.32

The pentasodium salt of 2-phosphonobutane-2,3,4-

- tricarboxylic acid is obtained by hydrolyzing the ester EXAMPLE 4 0.224 mole of ethane-1 ,1-diphosphonic acid tetraisopropyl ester was reacted at about to l 10C with an equimolar quantity of maleic acid diethyl ester in the presence of 15 ml of a saturated sodium ethylate solution. The reaction product was hydrolyzed by boiling with concentrated hydrochloric acid.

Following acid hydrolysis of the ester, the NaCl formed was separated off and the remaining sodium ions removed by ion exchange. The crude 2,2-diphosphonobutane-3,4-dicarboxylic acid was obtained in the form of a semi-solid paste by concentrating the solution.

EXAMPLE 5 0.5 mole of maleic acid dibutyl ester was reacted at about 100C with 0.5 mole of phosphonoacetic acid triethyl ester in the presence of 20 ml of saturated sodium ethylate solution. The sodium alcoholate was neutralized with acetic acid and the reaction mixture was distilled in vacuo (195 to 205C; pressure 0.3 mm Hg).

The ester thus obtained was hydrolyzed by boiling with hydrochloric acid. The l-phosphonopropane- 1,2,3-tricarboxylic acid obtained by concentration was converted into the pentasodium salt with sodium hydroxide at a pH-value adjusted to 12. The salt was obtained in crystalline form by the addition of methanol. The atomic ratio PzCzNa was 1:6.3:4.9 (calculated 1:625).

EXAMPLE 6 The complex-forming capacity of the compounds identified below with respect to calcium was determined by the so called Hampshire test. In this method, 1 g of the substance was dissolved in 100 ml of water, the resulting solution was adjusted to pH 12 with 2 N sodium hydroxide and ml of a 2 soda solution added. Calcium chloride solution was then added dropwise until a permanent haze was formed, the pl-l-value being kept constant.

(mg CaCo l g of substance) amounted to 600 for l-phosphonopropane-l,2,3-tricarboxylic acid 870 for l,1-diphosphonopropane-2,3-dicarboxylic acid 260 for 1-phosphonobutane-2,3,4-tricarboxylic acid 1,100 for 2-phosphonobutane-2,3 ,4-tricarboxylic acid 1,400 for 2,2-diphosphonobutane-3,4-dicarboxylic acid EXAMPLE 7 The complex-forming activity with respect to iron in a soda-alkaline solution of l-phosphonopropane-l,2,3- tri-carboxylic acid and l, 1-diphosphonopropane-2,3- dicarboxylic acid is shown in the following Tables. The following test arrangement was used: in each test, m1 of a solution containing 5 mMol (millimoles) of soda were added to 10 ml of a 0.01 molar FeCl solution. Increasing quantities of the complex formers specified in Tables 1 and 2 were added to these solutions, followed by heating to boiling point.

TABLE Z-continued Complex former mMol Precipitation no precipitation precipitation in hydroxide form.

EXAMPLE 8 The complex-forming activity with respect to copper in a soda-alkaline solution of l-phosphonopropane- 1,2,3-tricarboxylic acid and 1,1-diphosphonopropane- 2,3-dicarboxylic acid is shown in the following Tables. The following test arrangement was applied: in each test, 15 ml of a solution containing 5 mMol of soda were added to 10 ml of a 0.01 molar CuCl solution. Increasing quantities of the complex formers specified in Tables 3 and 4 were then added to these solutions, followed by heating to boiling point.

no precipitation precipitation in hydroxide form EXAMPLE 9 Table 5 below illustrates the complex-forming capacity of l-phosphonobutane-2,3,4-tricarboxylic acid with respect to iron and copper in a soda-alkaline solution. 15 m1 of a solution containing 5 mMol of soda were added to 10 ml of 0.01 molar FeCl and CuClsolutions for the purposes of determination. The complex former was added to these solutions in increasing quantities, as shown in Table 5:

TABLE 5 Concentration in mMol Fe+++ Cu++ precipitation in hydroxide form no precipitation EXAMPLE 10 The organic compounds mentioned in Example 1 in the form of their alkali metal salts were added in quantities of from 2 to 50 mg/l to water samples of different hardness heated to elevated temperatures. In this way, incrustation in the apparatus, especially the heating units, was largely suppressed because the precipitations are almost completely amorphous and consequently do not lead to incrustation. The use of larger quantities actually produced a marked overall decrease in the precipitations.

EXAMPLE 1 1 A product of the following composition was used in a concentration of l to 2 as a bottle-washing agent which prevents devitrification, even in the event of prolonged application in the warm-water zone:

78 7c of caustic soda 4.5 of sodium silicate (SiO- Na O 3.35)

1.75 7: of an anti-foam agent 5 7c of l,l-diphosphonopropane-2,3-dicarboxylic acid in the form of its sodium salt Balance sodium sulfate EXAMPLE 1?.

Beer bottles, lemonade bottles and mineral-water bottles were washed in a conventional bottle-washing machine with a solid washing agent of the following composition:

6O of caustic alkali 7c of trisodiumphosphate. anhydrous 5 of sodium silicate (SiO Na O 3.35)

2.5 of a non-ionogenic anti-foam agent 1.25 of l-phosphonopropane-l,2,3-tricarboxylic acid in the form of its sodium salt L 7c of amino tri-(methylene phosphonic acid) in the form of its sodium salt 10 of sodium sulfate.

The washing agent was used in a concentration of 1.5 7(

in the washing solution, which was heated to a temperature of approximately 75C. Even after prolonged use, there was no sign of any coating or scale formation in the washing machines.

EXAMPLE 13 A cleaning agent of the following composition was used in a concentration of 0.5 70 for cleaning metal components:

44.0 7c of trisodium monophosphates 50 7c of sodium metasilicate 1.5 of a non-ionogenic wetting agent 4.5 7c of l,l-diphosphonopropane-2,3-dicarboxylic acid in the'form of its potassium salt.

EXAMPLE 14 EXAMPLE 15 Beer bottles were washed in a conventional bottlewashing machine with two washing compartments. A washing solution which contained 1 of sodium hydroxide and to which an active concentrate of the following composition was added in a concentration of 0.2 7t. was used in both washing compartments:

30 "/r of phosphoric acid 6 7( of l,l-diphosphonopropane-Z.3-dicarboxylic acid 6 of amino tri-(methylene phosphonic acid) 20 7( of a non-ionogenic wetting agent (reaction product of polyglycerol with 7 mols of propylene oxide) Balance water The washing solutions were used at a temperature of about 60C and replenished as required by the addition of sodium hydroxide and the active concentrate. There were no signs of any scale formation in the warm-water zone, even after prolonged use.

What is claimed is:

1. A compound of the formula wherein X is selected from the group consisting of wherein M is selected from the group consisting of hydrogen, alkali metal and ammonium and R is selected from the group consisting of hydrogen, or alkyl radical with l to 4 carbon atoms and a phenyl radical and complexes thereof with alkaline earth metal ions.

2. A complex of claim 1 wherein M is sodium and the alkaline earth metal is calcium.

3. A complex of claim 1 where the alkaline earth metal ions are selected from the group consisting of magnesium, calcium, strontium, barium and mixtures thereof.

4. A compound of claim 1 wherein M is hydrogen.

5. A compound of claim 1 which is l-phosphonopropane-l, 2, 3-tricarboxylic acid.

6. A compound of claim 1 which is l. l-diphosphonopropane -2,3-dicarboxylic acid.

7. A compound of claim 1 which is l-phosphonobu tane -2, 3, 4-tricarboxylic acid.

8. A compound of claim 1 which is 2-phosphonobutane-2, 3, 4-tricarboxylic acid.

9. A compound of claim 1 which is 2, 2,-diphosphonobutane-3, 4-dicarboxylic acid.

10. A complex of claim 1 which is 2-phoshonobutane-2, 3, 4-tricarboxylic acid sodium salt complexed with calcium ions.

UNITED sTATEs PATENT AND TRADEMARK oEEIEE QETIFICATE OF CQRRECTIQ PATENT No. 3,923,876 DATED I Dec. 2, 1975 iNVENTUR(S) Heins et a1 it is certified that error appears in the above-identified patent and that said Letters: Patent is hereby corrected as shown below:

Col. 8, Claim 1, line 4 Cancel (ZOOM (200M IIO M C-CH -cand substitute therefor COOM (FOOM O M,

|CH2, and -cgigncd and Scaled this Sixth Day Of August 1985 [SEAL] A Arrest:

DONALD J. QUIGG Attesting Officer Acting Commissioner of Parents and Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 3,923,876

DATED Dec. 2, 1975 mvemonts) Heins et a1 It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

Col. 8, Claim 1, line 4 Cancel (ZOOM (300M 0 14 CCH -c- 2 I I l and substitute therefor COOM (rOOM IIO M I CH -(fand C Signed and Scaled this Sixth D a y of August 1985 [SEAL] Attest:

DONALD J. QUIGG Attesting Officer Acting Commissioner ofParents and Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 3,923,876

DATED Dec. 2, 1975 |NVENTUR(S) Heins et a1 It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

Col. 8, Claim 1, line 4 Cancel :00M (300M $0 14 -C-CH -c- 2 r f H R and substitute therefor COOM 00M 0 14 CH and -c- 2 f H R Signed and Scaled this Sixth Day of August1985 [SEAL] Attest:

DONALD J. QUIGG ling Officer Acting Commissioner 0 f Patents and Trademarks 

1. A COMPOUND OF THE FORMULA
 2. A complex of claim 1 wherein M is sodium and the alkaline earth metal is calcium.
 3. A complex of claim 1 where the alkaline earth metal ions are selected from the group consisting of magnesium, calcium, strontium, barium and mixtures thereof.
 4. A compound of claim 1 wherein M is hydrogen.
 5. A compound of claim 1 which is 1-phosphonopropane-1, 2, 3-tricarboxylic acid.
 6. A compound of claim 1 which is 1, 1-diphosphonopropane -2,3-dicarboxylic acid.
 7. A compound of claim 1 which is 1-phosphonobutane -2, 3, 4-tricarboxylic acid.
 8. A compound of claim 1 which is 2-phosphonobutane-2, 3, 4-tricarboxylic acid.
 9. A compound of claim 1 which is 2, 2,-diphosphonobutane-3, 4-dicarboxylic acid.
 10. A compleX of claim 1 which is 2-phoshonobutane-2, 3, 4-tricarboxylic acid sodium salt complexed with calcium ions. 